Potential killing freeze to affect Iowa crops
September 13th, 2011 by Ric Hanson
Weather and crop experts are expressing cautious optimism that Iowa’s corn, soybean and hay crops won’t be greatly affected by the frost predicted for north-central and northwest Iowa Thursday morning. The U-S-D-A estimates about one-third of Iowa’s corn crop is fully mature and most areas need another 10-days to reach that level. That’s why Iowa State University corn specialist Roger Elmore doesn’t believe freezing temperatures will greatly affect yields. “What that’ll do is shut the plant down and it will result in some reduction in yield, maybe at the most three to five percent,” Elmore said. “That yield reduction is coming from those kernels being shortchanged the last few days…so it’ll be a reduction in kernel weight.” Iowa State University Climatologist Elwyn Taylor says cloudiness in the approaching cold air could mitigate the frost damage.
“If it’s a perfectly clear sky, then we will get at least (a partial) killing freeze,” Taylor said. “That means, maybe not whole fields, but spots when we go through Wednesday night. We don’t expect it to stay around long. It would just be that one night with the killing freeze, which is basically 28-degrees for corn and soybeans.” I-S-U forage specialist Steve Barnhart says grasses respond well to cool temperatures, so the badly-needed late fall hay crop should be fine.
“A standing alfalfa crop and grass hay crops will tolerate a light frost and really won’t stop their growth for the remainder of the season,” Barnhart said. “It takes a 23 or 24 degree overnight freeze to really stop the hay crop.” The National Weather Service has issued a Freeze Watch for late Wednesday night through Thursday morning over north-central and northwest Iowa.